High-prevalence mental health problems require innovative strategies to broaden reach of evidence-based services. Disruptive behavior problems (DBPs), or conduct problems, in young children represent a major public health challenge that is not only highly prevalent but also, left untreated, heighten risk for adverse mental health and developmental outcomes in adolescence and adulthood. New, efficacious intervention strategies that can be delivered with sufficient reach in a resource effective manner are needed. Internet and online technology has considerable potential to help achieve such a goal. Building on parenting interventions that have demonstrated impact on childhood DBPs, this project compares an Online-Delivered Intervention to a well-validated Staff-Delivered Intervention, holding program content constant. The sample includes families with a 3-7 year old child who has a pronounced level of DBPs. Both interventions encourage fathers as well as mothers (and other key caregivers in the home) to participate. This innovative study makes use of a non-inferiority trial design that builds on methodological strengths: stratified random assignment, adequate statistical power, attention to fidelity of intervention, multi-informant and multi-source assessment of outcomes (including direct observation of parent-child interaction), and documentation of participant adherence. The aims of the project are: (1) to test whether the online intervention is as good as the more established staff-delivered intervention with respect to impact on childhood DBPs, parenting, and parent/family stress; (2) to conduct a rigorous value analysis comparing the two interventions, accounting for provider and participant expenses as well as pre-implementation and implementation phases; (3) to assess consumer satisfaction for the online intervention in comparison to the other intervention, as well as detailed consumer appraisal of the online intervention experience, and to explore how logistical factors, participant characteristics, and personal preferences are related to degree of consumer satisfaction; and, (4) to document participant adherence to the online intervention in comparison to the other intervention, and explore correlates of participant adherence for each intervention. The Online-Delivered Intervention provides an interactive website designed to engage and activate the participant through sequenced, personalized, interactive, and video-based content. The conceptualization that guides the intervention emphasizes a self-regulatory process, parent specification of goals, practical and straightforward parenting strategies, modeling, and action activation. Beyond shedding light on the impact and benefits of a viable online parenting intervention for childhood disruptive behavior problems, the results from this project will help the mental health field to better understand more generally the potential advantages and disadvantages of online interventions over traditionally delivered interventions, particularly in light of resource minimization/effectiveness analysis.